Polymers of carbon monoxide and olefins, such as ethylene, have been known and available in limited quantities for many years. For example, polyketones are disclosed in Kirk-Othmer Encyclopedia of Chemical Technology, Second Edition, Vol. 12, p. 132, 1967, and in Encyclopedia of Polymer Science and Technology, 1968, Vol. 9, 397-402. It is known that polyketones are prepared by contacting CO and ethylene monomers in the presence of a catalyst. High molecular weight polymers of ethylene which contain small quantites of carbon monoxide can be prepared with the aid of Ziegler catalysts. Low molecular weight polymers of carbon monoxide with ethylene and possibly other olefinically unsaturated hydrocarbons in which all monomer units occur distributed at random within the polymer can be prepared with the aid of radical catalysts such as peroxides. A special class of the polymers of carbon monoxide with ethylene is formed by the high molecular weight linear polymers in which the monomer units occur in alternating order and which polymers consist of units with the formula --CO--(C.sub.2 H.sub.4)--. Such polymers are prepared with the aid of, among others, phosphorus-, arsenic-, antimony-, or cyanogen-containing compounds of palladium, cobalt or nickel as catalysts.
High molecular weight linear alternating polymers of carbon monoxide and ethylene, consisting of units of the formula --CO--(C.sub.2 H.sub.4)--, can be prepared by using catalyst compositions comprising:
(i) a compound of a Group VIII metal selected from the group consisting of palladium, cobalt and nickel,
(ii) a bidentate ligand of the general formula ##STR3## wherein M represents phosphorus, arsenic or antimony, R is a bivalent organic bridging group containing at least two carbon atoms in the bridge and R.sup.1, R.sup.2, R.sup.3 and R.sup.4 represent hydrocarbyl groups which may be substituted with polar and nonpolar groups, and
(iii) a non-hydrohalogenic acid having a pKa less than 6.
Application of these catalyst compositions to a monomer mixture which, in addition to carbon monoxide, comprises for example ethylene and one or more alkenicallly unsaturated hydrocarbons having the general formula C.sub.x H.sub.y leads to the formation of polymers with units of the formula --CO--(C.sub.2 H.sub.4)-- and units of the general formula --CO--(C.sub.x H.sub.y)-- occurring randomly distributed throughout the polymer chains. The structures of the copolymers and `terpolymers` only differ in that in the case of the `terpolymers` a group --(C.sub.x H.sub.y)-- is encountered at random places in the polymer instead of a --(C.sub.2 H.sub.4)-group.
Such polymers can also be prepared by using catalyst compositions based upon:
(1) a compound of a Group VIII metal selected fron the group consisting of palladium, cobalt and nickel,
(2) a nitrogen ligand of the general formula ##STR4## wherein X and Y represent similar or different bridging groups, each containing three or four atoms in the bridge at least two of which are carbon atoms, and
(3) an acid with a pKa of less than 6, such as para-toluenesulphonic acid or a metal salt of such an acid, for example a tin or germanium salt.
The activity of catalyst compositions based upon components (1), (2) and (3) is to a great extent dependent on the nature of the component (3). The use of para-toluenesulphonic acid as component (3) yields catalyst compositions with a very attractive activity, but this activity is lost when the paratoluenesulphonic acid is replaced by an hydrohalogenic acid, such as hydrochloric acid. The same phenomenon is observed upon replacing the para-toluenesulphonic acid by an halide of tin or germanium, such as a chloride, as component (3). This likewise resulted in a total loss of activity in the catalyst composition containing a nitrogen bidentate ligand.
The catalyst compositions based upon components (i)-(iii) having a phosphorus, arsenic or antimony bidentate ligand for component (ii) react to the use of a hydrohalogenic acid for component (iii) in a way analogous to that of the catalyst compositions based upon components (1)-(3) which have a nitrogen bidentate ligand for component (2). In catalyst compositions based upon components (i)-(iii) and having a phosphorus, arsenic or antimony bidentate ligand for component (ii) the use of para-toluenesulphonic acid for component (iii) results in catalyst compositions having a very attractive activity, whereas this activity is lost almost completely when the para-toluenesulphonic acid is replaced by a hydrohalogenic acid, such as hydrochloric acid.
In view of the disappointing results obtained with hydrohalogenic acids as the third component in catalyst compositions containing a nitrogen bidentate ligand or a phosphorus, arsenic or antimony bidentate ligand, as well as the equally disappointing results from the use of halides of tin or germanium as component (3) in the catalyst compositions based on components (1)-(3), it was assumed that halides of tin or germanium would not be suitable for use as the third component in catalyst compositions based on components (i)-(iii).